Arkansas HVACR NewsMagazine March 2026

HVACR NewsMagazine March 2026

Tech News

vapor barriers. They usually come in the form of a highly permeable membrane, greater than 20 perms (required by code, but 50 perms or greater is often better). The sheathing terminates just shy of the ridge, the membrane fills that gap between the sheathing on each side, the membrane is adhered with proper air-sealing tape and flashing tape, and then a ridge cap conceals the membrane and allows air to pass over it. Keep in mind that vapor diffusion ports are approved by code for use in climate zones 1, 2, and 3. They can cause more problems than they solve in cooler climates, including microbial growth on the roof decking (which is what we’re trying to avoid in the f irst place). Again, is poorly designed venting the only reason why ducts and air handlers sweat in the attic? No, but they’re something we shouldn’t ignore. The reality is that air and moisture movement are important and will happen in an attic. Vent (or vapor diffusion port) design can either facilitate that movement or disrupt it and cause moisture to remain in the attic… and roof rot and needless duct sweating. Yes, these design factors are usually up to the builder, and the average HVAC tech or installer has no say in it. But we can still be mindful of that potential problem source, and in the case of knee walls, installers can make a choice to install the air handler as far away from those as possible to reduce the likelihood of sweating there. This article was furnished by the generosity of Bryan Orr, HVAC School by Techs for Techs. Bryan has become one of the most respected sources of technical information for our industry. We encourage you to subscribe to their podcast and articles at https://hvacrschool.com/

Wow! Your head is probably spinning and you may be wondering why you cared to read this article in the first place. Well, the HVACR industry always gets blamed for humidity problems. We may not have caused the problem but we are expected to solve it — even before it is apparent. Bryan took a deep dive into understanding attic designs and we need to understand all we can. This is especially true with encapsulated houses; however, don ’t blame everything on foam as though there was no mold until foam showed up. On contrar, we ’ve all seen drafty houses with mold in the bathrooms for years. Back to foam. The Association purchased a membership in the Spray Polyurethane Foam Alliance so we could access their information. They have “ like a ” library of articles that dig deep into proper application and installation of foam. Much of the information we used in the CE classes on foam came from the SPFA. So what does all this mean to our industry? It means that we have to be current on the entire system called a home. We don ’ t live in a 5 ton AC with a 100,00 furnace world anymore. If we are responsible for heating, cooling, and controlling the humidity, we must know what the system is going to throw our way. So learn, learn, and learn some more. It is a challenge and an opportunity.